[Comparison of tests for SS-A/Ro, Ro52 and Ro60 in predicting congenital heart block]

Neonatal lupus erythematosus (NLE) is a rare syndrome caused by the transplacental passage of maternal autoantibodies. Anti SS-A antibodies of a mother with Sjögren syndrome are associated with congenital heart block (CHB) in the newborns with NLE. The purpose of this study was to investigate the utility of maternal antibody titers for SS-A, Ro52 and Ro60 in mothers of newborns with CHB. The study involved a total of 304 cases, 25 from mothers of newborns with CHB, 104 from mothers of newborns without and 175 from mothers suspected to have connective tissue diseases. All sera were tested with the EliA SS-A, EliA Ro52, EliA Ro60, MESACUP Ro52 and MESACUP Ro60. The concordance rate of Ro52 assays was 93.4%, whereas Ro60 assays showed a lower concordance rate (74.7%). The areas under the curve (AUC) of the EliA assays were higher than those of the MESACUP assays. The optimal cut-off values for EliA SS-A/Ro and EliA Ro60 as derived from the ROC analysis were 2027 U/mL and 2446 U/mL, respectively. The sensitivity and specificity for EliA SS-A using optimal cut-off values were 96.0% and 92.3%, respectively. A titer of 90% positive predictive value for EliA SS-A was reached at a cut-off of 9897.1 U/mL, corresponding to sensitivity and specificity values of 36.0% and 100%, respectively. In conclusion, the optimal cut-off value for EliA SS-A is likely to be useful for application in clinical practice for the EliA SS-A measurements in mothers to evaluate the risk of NLE for their newborns.